Apple played to its audience at the conference for third-party developers, hoping to keep them enthused, informed and devoted when it comes to designing hip, fun or functional apps.

Cook devoted a chunk of the keynote to a software development kit he billed as the biggest release since the launch of the App Store.

Apple also debuted a programming language called Swift, to allow developers write programs that are faster, modern, safer and more interactive than they would be under its pre-decessor Objective C.

Doors opened by Apple for developers included letting applications once kept separate in "silos" work with one another.

Examples given included a Bing language tool being able to swoop in to translate a Safari browser Web page, or being able to "pin" a Web photo directly from Safari to online bulletin board Pinterest.

Apple also opened up its recently introduced Touch ID fingerprint recognition capability to third-party apps, giving the potential for it to become a security feature in more programs.

Apple CEO Tim Cook introduces the new IOS 8 mobil operating system during his keynote at the Apple Worldwide Developers Conference (WWDC) 2014 in the Moscone Center in San Francisco, California.

HealthKit was said to provide a secure haven for data collected by devices such as fitness bands that track activity and sleep.

Health-related information can now be collectively managed on Apple devices which could then watch for signs of trouble and even fire off messages to doctors when warranted.

HomeKit would let iPhones or iPads be used as a centralized control for Internet-linked gadgets such as door locks, lights, thermostats and security systems.

"We thought we could bring some rationality to this space," Apple senior vice president of software engineering Craig Federigh Federighi said while demonstrating HomeKit.

Apple senior vice president of Software Engineering Craig Federighi speaks during the Apple Worldwide Developers Conference at the Moscone West center in San Francisco, California. (AFP Photo)

Apple came up with a common network protocol, so not only can an iPhone be used to open smart locks but virtual assistant Siri can dim lights and lower thermostat settings when told "Get ready for bed."

Apple also beefed up graphics and speed capabilities for games, which are consistently among the hottest applications on its mobile devices.

"This is an incredible set of features; an incredible release," Cook said. "iOS 8 overall is huge for developers and massive for everyone else."

Apple has sold more than 800 million mobile devices powered by iOS; more than half of those being iPhones, according to Cook.